This invention relates to a process for fabricating a coating layer on a portable support and to a support provided with such layer.
The portable supports concerned by the present invention are objects of normalized size which may be carried without difficulty by their owner, for example in a pocket. They particularly concern card format supports such as chip cards or badges whose most frequent use is holder identification, giving the latter rights such as access rights or rights to conduct various banking operations.
At the present time, these card format portable supports are normalized. The usual ISO 7810 standard determines a standard card size that is 85 mm long, 54 mm wide and 0.76 mm thick.
To fabricate a card of the prior art, first a card body is produced which is printed and covered with a thin, transparent layer of polymethylmethacrylate (PMMA) transferred from a transfer film.
In practice, transfer films are multilayer films formed by coating or lamination. They are made up of a support layer in polyethylene terephtalate (PET) having a surface varnish and separated from the coating layer by a detaching or releasing layer made up of an adhesive, for example polyvinylbutyrate (PVB) or products of similar type. Another layer or adhesion layer may be added to the coating layer to promote adhesion of said coating layer onto the support. In one example, this adhesion layer is a copolymer of polyvinyl chloride (PVC)/polyvinyl acetate chloride (PVAc) type.
When a film such as described above is applied to the surface of the card body, and is exposed to a source of heat from an electronic heating head for example, the detachment layer separates and the coating and adhesion layers adhere to the surface of the card, naturally, under the effect of heat.
After transfer, however, it is not possible to modify the characteristics of the coating layer.
Also, since the coating layer is thermoplastic, it has little or no cross-linkage, softens under heat and has little resistance to abrasion and some solvents.
The objective of the present invention is to provide a new process for fabricating a coating layer on a portable support and also a portable support provided with such layer, which remedy the above-mentioned disadvantages at low cost and which can be used in particular to obtain supports whose coating layer provides suitable adhesion and has improved resistance to heat, abrasion and solvents.
This objective, and others which will be seen below, is achieved through a stage comprising cross-linkage or post cross-linkage of a thermoplastic layer so as to make it thermosettable.
Under a first variant to implement one embodiment of the invention, a thermoplastic layer is deposited on the support and is then cross-linked to improve its characteristics, and under a second variant for the implementation of this embodiment a post cross-linked coating layer is made which is deposited on the support with a suitable adhesion layer.
The object of the invention, therefore, is a process for fabricating a portable support, particularly a card format support, comprising a support body provided, on one of its sides, with a coating layer, characterized in that to fabricate said coating layer:
a transient thermoplastic layer is cross-linked to make it thermosettable.
Also, the object of the invention is a portable support, particularly a support of card format, comprising a support body provided, on one of its sides, with a coating layer, characterized in that said coating layer is a post cross-linked, thermosetting a layer.
The following description, which is in no way restrictive, will give a better understanding of the manner in which the invention may be put into practice.